It is suggested that a 1/2 stainless steel pipe about 40 feet long
packed with activated charcoal be used to trap out the Krypton
and Xenon and other gases from the recombiner. Since a charcoal
trap is poisoned by water vapour, this will necessitate a cold trap
between the recombiner and the charcoal line. The temperature
should be maintained less than - 20°C.